I recently bought a Samsung Galaxy 9S+. And for whom? For my wife from Thailand! And she has been using it to call me in and out of Thailand, with Internet, WiFi and What's App, Line, Viber, Messenger etc. Of course, you can put a foreign SIM in a Samsung Galaxy S9 plus if you bought it NEW and NOT BLOCKED, so you paid full price in the shop. Don't worry. But as I said, you must have paid the full price of a NEW device. Is this information enough or do you want to know more?